Means for varying the period of oscillation of two oscillatory circuits.



R. H. RENDAHL.

MEANS FOR VARYING THE PERIOD OF OSGILLATI ON OI TWO OSGILLA'IORY CIRCUITS.

APPLICATION FILED SEPT B, 1909 1 ;7 Patented Jan. 16, 1912.

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UNITED STATES OFFICE. u RAGNAR Iranian RENDAHL, F srocKHoIZM, SWEDEN, AssIeNon TO eEsELLscHaF'r mm DRAHTLOSE TELEGRAPHIE, M. B. H oi" BERLIN, GERMANY.

MEANS FOR VARYING THE PERIOD OF OSCILLATION OF TWO OSCILLATORY- CIRCUITS.

Specification of Letters Patent.

Application filed September 8, 1909. Serial Iva 516,702.

' To all whom it may concern:

Be it known that I, RAGNAR Hit KAN -RE1v- DAHL, a subject of the King of Sweden, and

residing at Stockholm, Swedem'have in-. .vented a certain new and useful Improved Means for Varying the Period of Oscillation of Two Oscilla-tory Circuits, of which the following is a specification.

'Ihe subject;1natter of my invention comprises means for varying the period of oscillation of two oscillatory circuitstuned oneto the other.

Recently almost all stations forwireless telegraphy and telephony have been so ar ranged that they can emit and receive oscillations of different wave-lengths, So long as they operate with simple transmitters and receivers the'variation of the wave-length is brought about simply by altering the constants of the antennae, e. g. the capacity or self-induction. Conditions are different in case of a coupled system; for in this event when changing from one wave-length to' another the tuning of all circuits of thes'tation must be altered simultaneously. In general, thisa'lteration is brought about for example at the transmitter by increasing or diminishing the self-induction of the .aerial and corresponding variation of the capacity or self-induction of the primary circuit. Other methods havealso been proposed; all have the common disadvantage, however, that when the wave-length changes the coupling between the different circuits is altered without following a definite law. Sometimes it becomes closer, sometimes looser, so that in coupled systems it is necessary to adjust the coupling in addition to altering the constants of the different oscillatory circuits.

Now the principal object of my invention is to do away with this drawback.

According to my invention the capacity of the two circuits is made constant, the two circuits arecoupled directly, and the part of the self-induction of the circuit having the greater capacity, which serves for cou{ pling, forms a previously determined percentage of the entire self-induction of this circuit. This percentage is the same for all wave-lengths whenthe coupling coefficient is to be constant. Consequently it is most convenient in practice to make use of the total self-induction of the circuit which has the greatest capacity for coupling, whereas the remaining portion of the self-induction of the circuit, having the smaller capacity is not used for coupling. In this case the coupling Patented Jan. 16,1912.

coefficient is determined theoretically by the simple formula aye 2,

when 0 and 0 are the capacities. If, however, it is not desired to keep thecoupling coefficient constant, but to increase it, e. 9., gradually with the Wave-length in such manner that for short waves the coupling my invention, and Fig. 3 shows the same arrangement when the entire self-induction of the primary circuit is not to be made use of for coupling but only a part of the same; Fig. 4 shows diagrammatically an arrange ment in which the coupling for short waves is looser than for long waves. Similar reference characters parts inall views.

'Referring to the drawings and firstly to Fig. 1, a designates afixedcondenser, b a spark-gap, c a variable self-induction, d an aerial, e a variable self-induction, f an earth connection. The variable self-inductions a and 6 must be arranged relatively to one another in'such manner that they do not in fluence the coupling.

.In Fig. 2 the self-induction 0 consists of two coils which can be rotated relatively to one another, so that the self-induction can be gradually varied. Preferably the circuit a, b, c is calibrated in wave-lengths. The self-induction of the aerial is represented by the coil 0 which can be varied-step by step and the gradually variable self-induction e Preferably the coil 6 is also calibrated. g designates a hot-wire ammeter or other suitable measuring or indicating instrument. In this. arrangement'the change designate like from one wave-length to another effected simply by the variable self-induction be- I ting-adjusted to the desired wave-length; the coil e isadjusted-similarly, whereas the gradually variable self-induction e is alwhich correspond to one another-a like color,

, or to. connect them positively one with the j other in such-,manner' that incorrect adjustw mentis avoided as much as possible.

. The proportion ofo to 0, however, remains" "constant andconsequently the coupling co- In -Fig'r3lthe coil cis'represented by a series of variometers which are positively. connected one with another. Of these variometers only a part0 is ."used' for-coupling.

" .eiiicie'nt also.

v F g.4 1s identicalwith.liigdliexcept'that (the-fixed self-induction h is provided here s which causes the coupling between the'pri- *mary circuit and aerial ,to become closer as the wave-length cuitshaving'constant capacity, variable self induct-ion and being galvanically coupled increases. Iclann: I p 1. The combination of twooscillatory cir- With and tuned one to the other, connections arranged so v that I the variations of the selfinduction results in the coupling self-indu'c 2 tion being for all wave-lengths a previously induction and being galvanically coupled determined percentage of the item self-in duct-ion of the circuit capacity. y I

The combination oftwo oscillatory cir-. cuits having constant capacity,va'riable self;

which has the reater with and tuned one .to ,th'e other, connections arranged so that the :variations of the self-induction results in'the "coupling self-' lnduction being for all wave-lengths an equal previously determined percentage of has the greater capacity.

to the co'upled' circuits andbeing arranged infla variomete'r, the self-induction'of the the total self-induction of the circuit which 1 6'0 3. Y The combination. of twooscillatory cir cuits having constant capacity, and J being galva'nically' coupled with and tuned one to the other, a self-induction bei.ng--- fcommon-- secondary circuitnotparticipatingon the ,coupling being arranged in a coil [variable by degrees and ya" fine tuning means (connected therewith, connections 'arranged'so that the variations .of the self-induction ;re-j suits-in the coupling self-induction being for a all wave-lengths a previously determined percentage of the,total 'self-inductio nof the circuitwhich has the greater capacity. 4. The combination of two oscillatory cirgalvanicallycoupled wit-hand tuned one to cuits having constantcapacity and being the other,;-. a series ofvariometers connected series andbeinggiiiechanically connected one wlth another to cause their -simultaneous .mechanical operation to the same'angular degree, apart-ofthesevariometers being si- ,multaneously electrically connected with the secondary .circuit, the couplingself-induction being for, all wave-lengths a previously determined portion of: said series of variometers.

5. The combinationo f'two oscillatory circuits having constant capacity, variable selfinduction and being galvanically coupled with and tuned one to the other, connections arranged so that .the variation of the selfinductions result-s ifithe coupling self-imduction being for all wave-lengths a previously determined percentage of the total selflinduction of the circuit which has the greater capacity, the latter.circuit'containing a constant self-induction. r t,

In testimony whereof, I afiix my signature in the presence of two witnesses.

RAGNAR HAKA' RENDAHL. Witnesses i EDWA D E. NICHOLSON,

'E. D. WINs oW. 

